Search results for "Littoral"
showing 10 items of 118 documents
The occurrence of Echinorhynchus salmonis Müller, 1784 in benthic amphipods in the Baltic Sea
2015
The acanthocephalan Echinorhynchus salmonis Muller, 1784 is a common parasite of salmonid fish, but it has rarely been reported from an intermediate host. Samples of benthic amphipods, Monoporeia affinis (Lindstrom), were taken from multiple, deep sites (usually below 70 m) in the Gulf of Bothnia over the course of more than a decade and examined for acanthocephalans. Overall, only 0.44% of 23 296 amphipods were infected, all with just a single worm. This prevalence is consistent with several previous reports of acanthocephalans in deep-water, benthic amphipods, but it appears low compared to that often reported for acanthocephalan species infecting littoral amphipods. Parasite occurrence d…
Aquatic biodiversity and saline lakes: Lake Bogoria National Reserve, Kenya
2003
Lake Bogoria, in the Rift Valley of Kenya is an extreme saline lake (conductivity 40–80 mS cm-1, alkalinity 1500 m equ 1-1). It is hydrologically more stable than the other, endorheic lakes in Kenya, because it is deep — maximum depth at present just over 10 m in an area of 3000 ha — and so does not have periods when it is dry. It is ecologically simple, with only one species dominating the phytoplankton — the cyanobacterium ‘spirulina’, Arthrospira fusiformis. Its biomass and productivity were very high — biomass between 38 and 365 μg 1-1 chlorophyll ‘a’ and 3.4–21 x 103 coils ml-1 and net production between 0.24 and 1 gm C m3 h, the latter in a narrow zone of less than a metre. There were…
Pattern and rate of post-20 ka vertical tectonic motion around the Capo Vaticano Promontory (W Calabria, Italy) based on offshore geomorphological in…
2014
The magnitude and rate of Late Pleistocene-Holocene vertical tectonic movements offshore of the Capo Vaticano Promontory (western Calabria, southern Italy) have been measured on the basis of the present-day depth variations of the edges of submerged depositional terraces (and associated abrasion platforms) that formed below the storm-wave base, during the sea level stillstand of the Last Glacial Maximum (LGM). These depositional features, represented by submerged prograding wedges and an associated terrace-shaped upper boundary, have been identified in high-resolution seismic reflection profiles acquired along the continental shelf and the upper slope of the promontory, and are referred to …
Isopoda Asellota de Turquie récoltés en 1987
1996
Asellus aquaticus is present in 19 of about 100 Turkish groundwater stations prospected during biospeleological explorations. All specimens of these stygophilic populations remain oculate, even though their integumental pigmentation is more or less reduced. Proasellus lykaonicus Argano & Pesce, 1978 has been found again in a second cave, nearby the type locality. A large and endemic, stygobiont species, Proasellus pisidicus n. sp., from phreatic groundwater, Vilâyet Burdur, and the minute Proasellus pamphylicus n. sp. from interstitial waters of the eastern part of Vilâyet Antalya are described. The stygobiont proasellids of Asia Minor, P. lykaonicus and P. pisidicus n. sp. belong to the sa…
L'Arctique en mutation
2016
International audience; AVANT-PROPOS..........................................Daniel JOLYCHAPITRE 1 - Fluctuations climatiques récentes en Arctique : l’exemple du Spitsberg occidental, Madeleine GRISELIN, Christelle MARLIN et Jean-Michel FRIEDTCHAPITRE II - Évolution contemporaine des glaciers arctiques ; exemple de l’Austre Lovénbreen (79°N), Eric BERNARD et Florian TOLLECHAPITRE III - Géomorphologie des côtes rocheuses arctiques, SAMUEL ETIENNE, Jim HANSOM et Donald L. FORBESCHAPITRE IV - L’Arctique face aux crises géomorphologiques paraglaciaires, Denis MERCIERCHAPITRE V - Distribution multi-scalaire de la végétation en Arctique, Martha RAYNOLDCHAPITRE VI - Distribution de la végétation …
Herbivore-Induced Changes in Cotton Modulates Reproductive Behavior in the Moth Spodoptera littoralis
2017
Plants produce chemical defense compounds to resist herbivore attack either by repelling the herbivores or attracting natural enemies of the herbivores. We have previously shown that volatile compounds from cotton released in response to herbivory by conspecifics reduce oviposition in cotton leafworm moth Spodoptera littoralis. It remained, however, unclear whether herbivore-induced changes also affect moth pre-mating and mating behaviors. In this study we examined the effect of herbivore-induced changes in cotton on reproductive behaviors i.e., female calling, male attraction and investment, and mating behavior in S. littoralis. We found a reduction in the number of females calling i.e., f…
TERRESTRIAL LASER SCANNING FOR COASTAL GEOMORPHOLOGIC RESEARCH IN WESTERN GREECE
2012
We used terrestrial laser scanning (TLS) for (i) accurate volume estimations of dislocated boulders moved by high-energy impacts and for (ii) monitoring of annual coastal changes. In this contribution, we present three selected sites in Western Greece that were surveyed during a time span of four years (2008-2011). The Riegl LMS-Z420i laser scanner was used in combination with a precise DGPS system (Topcon HiPer Pro). Each scan position and a further target were recorded for georeferencing and merging of the point clouds. For the annual detection of changes, reference points for the base station of the DGPS system were marked. Our studies show that TLS is capable to accurately estimate volu…
Invasive crayfish increase habitat connectivity: a case study in a large boreal lake
2013
Several studies have shown that distinct compartments of lake ecosystems are coupled via transportation of organic matter, nutrients and energy across habitat boundaries. Here we evaluate the potential of the invasive signal crayfish (Pacifastacus leniusculus (Dana)) to modify energy pathways in large boreal lakes. Using a stable isotope mixing model and calculation of the isotopic niches we estimated the contribution of different food sources to the diets of crayfish captured from different habitats, and from that inferred their potential to transport energy across the littoral-profundal gradient. The crayfish caught from the littoral area utilized mainly littoral food sources, whereas the…
Littoral contribution to whole-lake primary production in highly humic Lake Mekkojärvi
2013
Suurin osa koko järven perustuotantoa käsittelevistä tutkimusta on tehty oligotrofisissa tai eutrofisissa järvissä ja vähän on tutkittu dystrofisten järvien toimintaa. Tämän tutkimuksen tarkoitus oli selvittää litoraalivyöhykkeen perustuotannon osuutta koko järven perustuotannosta dystrofisessa Mekkojärvessä vuonna 2012. Mekkojärvessä on korkeat liuennen orgaanisen hiilen (DOC) ja humushappojen pitoisuudet ja näiden tuloksena erittäin matala valon tunkeutuvuus, suhteellisen matala ravinnepitoisuus ja suhteellisen korkea keskisyvyyden suhde maksimisyvyyteen. Mallit, jotka perustuvat edellä mainittuihin parametreihin, ennustavat pohjaleville vain 5 % osuutta kokonaisperus…
Accounting for littoral primary production by periphyton shifts a highly humic boreal lake towards net autotrophy
2016
1. The prevailing view that many humic lakes are net heterotrophic is commonly based on pelagicmeasurements alone. Poor light conditions in humic lakes are assumed to constrain littoral primaryproduction (PP), such that the littoral zone has been considered an insignificant contributor towhole-lake PP. However, that assumption is based on models and inferences from pelagic processeswhich do not take littoral zone structure into account. Many lakes have an extensive ring of aquaticvegetation lying near the water surface, which provides substratum for epiphytic algae under well-illuminated conditions.2. We measured both pelagic and littoral PP and community respiration (CR) in Mekkoj€arvi, a s…